1 Field of the Invention
The invention relates to the field of turbojets, more particularly that of interblade platforms for the blade support discs for turbojet blowers.
2 Description of the Related Art
Turbojet blowers (or fans), whose blades have a curved end, generally comprise blade support discs equipped with attached interblade platforms intended to optimize the flow of air between the blades, and more precisely to reconstitute the aerodynamic profile of the internal “stream” at the blades.
These attached platforms comprise a deflecting part whose lower face frequently comprises three fixing lugs (one upstream, one central and one downstream) intended to enable them to be fixed isostatically to a support disc. Two embodiments are normally encountered. The first embodiment consists of arranging the three fixing lugs in the form of flanges provided with an orifice for the passage of a fixing stud. The second embodiment consists of arranging two of the three fixing lugs in the form of flanges provided with an orifice for the passage of the fixing stud, and providing the third fixing lug with a fixing device of the bayonet type.
The attached platforms generally being metallic or composite, their three fixing lugs are formed by machining from a solid block. However, because of the presence of the upstream and downstream fixing lugs, accessibility to the central fixing lug is difficult, which makes it particularly tricky to machine. In addition, because of the presence of three fixing lugs the weight of the platforms is relatively great, which contributes to making the turbojets which they equip heavier.
In addition, when an incident occurs on a blade, for example because of the ingestion of a foreign body by the turbojet, the blade may move (or flex) and interfere with the lateral edge of one of the adjoining platforms. However, because of the method of fixing the platforms, when such an interference occurs, the said platforms deform whilst remaining substantially in place, which may cause significant damage at the blade, or even in the engine part of the turbojet situated downstream of the blades, and/or a loss of efficiency of the turbojet, or even cause it to be put out of service.